


A Simple Experiment

by gucciluigi



Category: BioShock, BioShock Infinite
Genre: F/M, Lutecest, Pegging, loud bottom and unimpressed top, sorta incest, sorta not incest
Language: English
Status: Completed
Published: 2014-11-04
Updated: 2014-11-04
Packaged: 2018-02-24 02:17:13
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,972
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/2564636
Author URL: https://archiveofourown.org/users/gucciluigi/pseuds/gucciluigi
Summary: <blockquote class="userstuff">
              <p>Rosalind and Robert are bored. They get kinky.</p>
            </blockquote>





	A Simple Experiment

Robert sat in the parlor of Lutece Laboratory, completely and utterly bored. He looked around at the thick tubes and wires running through the building, and then over at his sister, who was reading a book on physics and occasionally scoffing and making corrections. She finally slapped the book shut and placed it in her lap, looking over at her brother. 

"A theory," she began, her eyes searching her brother's body inquisitively. "Since we have nothing to do on this particular day and since DeWitt and Elizabeth are already well on their way in this particular tear and therefore do not need our assistance quite yet, I've an idea on how to entertain ourselves," she said, getting up and swishing towards the stairs towards her bedroom. Robert quickly got up and followed after her, only for her to stop abruptly at the top of the stairs to face him, pressing herself against him. This gave his normally shorter sister quite the height advantage, and her breasts were all but touching his nose, causing him to raise an eyebrow.

"And what are you suggesting, dear sister?" he asked, sort of curious as to her chosen placement of certain particular body parts, but not finding himself particularly wanting to move. 

"I've created a device that will allow me to anally penetrate you," she said, moving her hand to her alternate's hair. "I'm curious to see what I could do with it. Come up and help me test it," she ordered, taking his hands and pulling him the rest of the way up the stairs.  
He scoffed, but looked amused by the idea. This certainly wouldn't be the first time that he'd been the subject of his sister's experimentation. "Why, Rosalind, what ever would the wholesome, Godly denizens of Columbia think of their lady of science succumbing to the devilish temptation of incest? Unmarried incest, at that," he said, allowing her to lead him into the bedroom.

"Ah, but it's not incest. Not really, you know that. After all, if I cannot trust myself not to tell, who can I trust, dear Robert?" she quipped, pushing him down onto the bed. "Besides, I'm bored out of my skull. But if you'd rather go back down to the parlor and watch wallpaper peel, by all means," she said, pulling up her skirt and straddling him, pressing her mouth against Robert's and wrapping arms around his neck. The answer was given to her in the form of a chuckle and hands moving to her waist, his lips moving back against her's and opening when her tongue pressed against them for entrance to his mouth. This was a familiar game to them, the twins often engaged in such endeavors when there was time to kill, and being such inquisitive people they were often known to venture into unexplored sexual territory. 

She was already pushing off his suit jacket, undoing the buttons and pushing it off of him, then taking off her own jacket. She tossed it haphazardly on the floor. There would be time later to tidy up. She ran her fingers through his tightly coiffed hair, getting up to unbutton her vest and blouse. "Go on and remove the rest of your clothing for me, darling. I've got to go get the device." Half-dressed, she hurried past the whirring maching breaking through the floor of the bedroom to the bathroom to finish undressing and put on the strap-on she'd crafted from leather, complete with a dildo of a nice fiery red. She figured it would match. She walked back into the bedroom, her brother's eyes trained on the device strapped to her crotch.

"My, that's rather large, isn't it?" he asked in disbelief, laying back against the bed when Rosalind emerged, prompting her to crawl on top of her brother and lay kisses down his neck, the dildo pressing against his stomach. He looked nervous and seemed a bit skittish under her. This amused her greatly, and she was excited for what was to come.

"Yes, well. I figured you could handle it," she promised, her teeth worrying the crook of his neck. She loved the sight of it, red lipstick all over his pale skin, perfection marred by her cosmetics and the marks she would suck on him. She loved making her perfectly groomed brother look debauched and sexed up, it was a simple but overwhelmingly arousing pleasure. Her hand moved down, fingers caressing a semi-hard Robert, wrapping her hand around him gently and pumping slowly to wring quiet moans out of him. "Consider it a look from my perspective, all those times you've gone poking around with your prick in me. I've always been curious what it was like to have the upper hand, so to speak."

"Oh, I hate when you tease," he whimpered, her hand only seeming to move slower in response. She smirked. His voice was beginning to crack, and his want was beginning to show. She swirled her thumb around the tip of his cock, her faux one rubbing up against him, reminding him of the task at hand. She let go briefly, enjoying that delicious mewl of protest Robert let slip, to reach over to her bedside table and grab a clear vial of oil. She unscrewed the top and let some pour onto her fingers, making sure to coat them generously. 

He knew what was coming, and he spread his legs a bit in anticipation. Good heavens, he was a little more excited about this than he originally thought. She ran her clean hand down his thigh, gently pushing one slender finger against his entrance. He gasped a bit, and she pet his thigh. "Easy now, dear, this won't hurt but for a second," she promised, edging the tip into him. 

Robert listened to her and relaxed a bit before tensing right back up when he felt her penetrate him, making it very hard for her to push her finger all the way in. She sighed and wiggled the tip of her finger. "Robert, come now, how am I supposed to make this comfortable for you if you won't cooperate?" He made a whiny little noise and tried to relax his muscles. "There's a lad," she said, working her finger in as far as she could, crooking it and rubbing against the muscles in the other's body. 

"Go on, then," he urged. Just the one finger didn't quite hurt, it just sort of felt intrusive. But when Rosalind slipped in a second finger, he felt the sting he'd been expecting. He hissed quietly, looking up at his sister, her still pinned up hair, her beautiful breasts, her slender hips, the leather cinched tightly around them. It was as his eyes were traveling back up that he felt a tingly wave of pleasure spread through his body, his hips bucking upward and his head leaning back, letting out a loud moan. 

Rosalind chuckled. "I think I've done well, judging by the look on your face," she said, making a "come hither" motion with her finger and stroking the bundle of nerves she'd founded, coaxing such delicious noises out of Robert. "Yes, I believe that would be your prostate. I'll keep note that it causes you to make such pleasant sounds, that will prove useful in a few minutes, I'm sure," she said before pushing in her third finger, feeling her brother's muscles clench around her.

"Slower, a bit slower," he begged, now feeling stretched to his limits. It stung, oh it stung, but the way she was moving inside of him, it felt too good for him to ask her to stop. She kept at it, but she slowed just a tad, making sure not to hurt him. After all, if she hurt him, he wouldn't want to do this again and she couldn't have that. After what felt like far too long, she pulled her fingers from him, looking over his body and licking her lips just slightly. The way he was all spread out for her, the way his prick sat against his stomach and dripped a sticky little puddle of pre, the thought that it was all for her. Well, she intended to take advantage. She moved on top of him, pressing her breasts against his chest, guiding the tip of her dildo into him. 

The faux cock was much wider than her fingers, and Robert let out a pained whimper, but Rosalind kept pushing, burying it to the hilt in her brother. Robert panted and moved his hands to his sister's shoulders, his chest heaving. "Please don't move more yet, Rosalind, I fear it will tear me."

"It's not going to tear you," she insisted, but she waited at her brother's request, taking this opportunity to press more kisses down his neck. Her hands roamed down his chest, feeling how hard the other was breathing, feeling his cock twitch against her stomach. She supposed it would be the nice thing for her to do to take his mind off of his pain (she also figured it would expedite the process and allow her to start moving inside him sooner), so she wrapped her hand around his cock and allowed long, languid strokes, watching her brother's cheeks flush red as he let out a shaky breath.

It wasn't long before he uttered the word "move" under his breath, and so she did, her hips snapping forward and beginning to thrust into her brother, suspending herself above him and drinking in all of the moans and gasps that he allowed to escape. "My, you're quite the noisy little thing, aren't you?" she asked, pressing a kiss to the corner of his mouth to punctuate his moans. "It's broad daylight, you know, someone outside is going to hear you. Perhaps next time I shall gag you up, that way you'll be quiet as a church mouse, hmm?"

Robert couldn't help but shiver with arousal at the thought, his hips jerking up to meet Rosalind's as she plowed into him, his nails digging into her back. He was past the point of words now, the tip of her faux prick drilling endlessly into his prostate. Her hand moved steadily on his cock, matching the speed of her hips perfectly, switching up the pressure of her hand to give him the feeling of fucking into something. Oh, this wasn't going to be long, he could feel it build in his stomach, pangs of heat coarsing through his body as sweat collected on his brow.

She kissed it off, making sure to hit his favorite spot with precision. She could tell by the way pre dripped across her fingers in rivulets this was not going to be much longer, but she didn't mind. Just as she was thinking to herself what a rousing success this particular experiment had turned out to be, Robert ejaculated all over her hand and his stomach, crying out loudly and tipping his head back. She kissed the bottom of his chin, pulling out her dildo and wiping her hand off with the edge of her duvet. "Well now, you've made quite the mess but I should say that this has gone extremely well, wouldn't you agree? We shall have to try it again sometime, she said, unhooking the leather strap-on from her hips and lying next to her brother, placing her hand on his chest.

He nodded, still catching his breath and leaning over to kiss Rosalind. "Agreed. And I believe that once I'm able and ready, you should have your turn as well," he said and rolled to face her, taking her breasts into his hands and pressing soft kisses down her jaw. 

She chuckled warmly and moved her hands to Robert's waist, tilting her head up a bit. "Right, well, who am I to disagree?"


End file.
